The correct answer should be A. spores
Ferns don't have seeds and they reproduce using spores. Cones have seeds in them and seeds fall out. Pollen enters a flower and then the flower becomes a fruit. This is sexual reproduction of plants. Since ferns don't have this, they have to reproduce with spores.
Answer:
As the variables are not given, let us help with general explanation on manipulated variable.
Explanation:
A manipulated variable is an independent variable. In a scientific experiment, an independent variable can be described as a variable which can change naturally or which is changed by the researcher to check its effect on the dependent variable. The dependent variable is the variable which is under study and being tested.
For example, to check the difference in photosynthesis rate by light, the amount of light will be the independent variable and the rate of photosynthesis will be the dependent variable.
